DURABILITY OF A WELDED TRUSS UNDER CYCLIC LOADS

The paper presents the results of experimental studies of the durability of a rectangular welded truss. The truss is made of profile pipes with butt joint nodes. A concentrated cyclic load is adopted for the construction, which corresponds to the operating mode of the roof truss with the ways for the bridge crane. The study was performed using the method of semi-natural and computer simulation experiment in ANSYS Workbench 17 environment. It was found that the loss of bearing capacity by the truss during operation occurs due to the fatigue crack initiation in the K-shaped node on the upper chord of the truss. The durability of the truss is determined by the ratio of the parameters of force and time of operation of the truss. The results of the semi-natural and computer simulation experiment were verified and the fatigue damage indicators coincided at the level of 5.7%.Keywords: welded truss, fatigue damage, truss nodes, durability of the truss.

Collaborative Distributed Planning with Asymmetric Information. A Technological Driver for Sustainable Development

The growing interest in sustainable development is reflected in both the market’s sensitivity to environmental and social issues and companies’ interest in the opportunities that sustainable development objectives provide. SMEs, which account for most of the world’s pollution, have significant resource constraints for a sustainable development. Sharing their scarce resources can help them to overcome these constraints and to gain agility and organisational resilience against uncertainties, but the distrust inherent in belonging to different companies prevents them from sharing the necessary information for coordination purposes. This paper presents a coordination mechanism proposal with information asymmetry to allow independent companies’ resources to be sustainably shared as a technological driver. The proposed distributed coordination mechanism is compared to both a decentralised–uncoordinated and a centralised situation. The interest of the proposal is evaluated by a computer simulation experiment employing mathematical programming models with independent objectives in the Generic Materials and Operations Planning formulation with a rolling horizon procedure in different demand, uncertainty and product scenarios. Competitive improvement is identified for all members for their excess capacity use and their operations planning.

Fatigue damage of the heel joint of welded roof truss

The investigation of the welded roof truss behavior under the complex influence of static and cyclic loads is carried out. The truss is made of the shaped pipes and its size is 24000x2400 mm. The technique of computer simulation experiment by means of SolidWorks Simulation software is used. It is found that the maximum stresses are formed in the area of thermal impact from the weld in the truss heel joints. During the truss operation, these stresses initiate the emergence of fatigue cracks and their growth until the structure ultimate state. The fatigue curve for the investigated structure is constructed. It is determined that the design service life of the truss under operational load modes is going to be 52 years.

A Fast Sparse Recovery Algorithm for Compressed Sensing Using Approximate l0 Norm and Modified Newton Method

In this paper, we propose a fast sparse recovery algorithm based on the approximate l0 norm (FAL0), which is helpful in improving the practicability of the compressed sensing theory. We adopt a simple function that is continuous and differentiable to approximate the l0 norm. With the aim of minimizing the l0 norm, we derive a sparse recovery algorithm using the modified Newton method. In addition, we neglect the zero elements in the process of computing, which greatly reduces the amount of computation. In a computer simulation experiment, we test the image denoising and signal recovery performance of the different sparse recovery algorithms. The results show that the convergence rate of this method is faster, and it achieves nearly the same accuracy as other algorithms, improving the signal recovery efficiency under the same conditions.

Mathematical Model and Simulation for Testing Aspheric Surface Using the Digital Moiré Patterns by Circular Sub-Region Stitching Method

sub-region stitching measurement of asphere by using the combination of digital moire patterns without compensator, auxiliary mirror and other assistant modules. This paper illustrated the principal theory. And use of digital filtering, phase shifting, the least square method and Zernike polynomial fitting to establish the reasonable mathematical model. Meanwhile the computer simulation experiment was carried on. the PV and RMS of the full aperture phase distribution residual error are 0.058λand 0.0087λ After this method processing.

The construction of test reliability statistical criteria by a computer simulation

The paper describes a computer simulation experiment of knowledge assessment test when item’s characteristic functions are power functions and knowledge level of the population has uniform or normal distribution. The inversions of the conditional means were calculated and probability distributions of the numbers of inversions were simulated. In practice of construction of knowledge tests for checking their suitability (validity) observed values of inversions are compared with reference values obtained byMonte Carlo experiments.